Glucosamine is a substance that the human body makes naturally. It plays a structural role in the cartilage of joints and is in the liquid that cushions the joints. Humans synthesize glucosamine from the breakdown products of food, and it is not normally present in food. The health supplement market sells glucosamine in tablet or liquid form, as it may be useful for keeping joints healthy and improving the symptoms of arthritis.
Many different substances that are intrinsic to the functioning of the body can be made by manufacturers and sold as supplements to a normal diet. In the case of glucosamine, no normal food sources exist, but the chemical is present in high quantities in the shells of shellfish like prawns. Companies can crush up leftover shells from the fishing industry and extract glucosamine that way. Alternatively, a factory can make synthetic glucosamine, by mixing up different raw ingredients to get the required molecule.
There are three main forms of glucosamine in the market, which are glucosamine hydrochloride, glucosamine sulfate, and n-acetyl glucosamine. These vary slightly in molecular structure and are available as tablets, powders or liquids. Different structural forms can also have varying effects on the body, and most of the scientific evidence to back up the effects of glucosamine are based on glucosamine sulfate. This particular form of liquid glucosamine supplement is the same form as that present in the body.
The sulfate form of liquid glucosamine is the type which has the most scientific evidence to back up its use as a supplement. It appears to reduce pain in people with a particular form of arthritis called osteoarthritis, but the evidence, as of 2011, is not yet conclusive. The pain relief, if present, generally takes a few months of supplements to occur. Glucosamine sulfate may also be beneficial to joint health in those people who already have osteoarthritis.
Typically, people who take liquid glucosamine take it daily. About 1500 milligrams of the substance, typically in a spoonful of the liquid, is a commonly recommended dose by the manufacturer of the product. As well as a liquid glucosamine ingredient, the product generally includes sweeteners and water to make the liquid palatable. Some products contain extra ingredients that may also be useful for joint health. These include chondroitin, which is another component of joints, and manganese, which is a trace element involved in bone maintenance.
Although glucosamine is naturally present in the body, it can have adverse effects as a supplement. Kids should not take the supplement, as its effects have not been studied in that age group. People on insulin for diabetes, or who take blood thinners, can suffer problems as glucosamine can produce adverse effects in the presence of these drugs, among others.